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Method and apparatus for discrimination between different kinds of data transmission

  • US 4,850,008 A
  • Filed: 02/29/1988
  • Issued: 07/18/1989
  • Est. Priority Date: 02/29/1988
  • Status: Expired due to Fees
First Claim
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1. In the operation of a data communication station comprising a first data terminal operating under a first transmission standard under which an incoming call starts with a preliminary ring signal and a subsequent recognition signal, a second data terminal operating under a second, different transmission standard under which an incoming call starts with a preliminary ring signal and may include a subsequent recognition signal, and selective switching means for connecting a telephone line or like communication line to either of the data terminals for completion of an incoming call that starts with a ring signal, in which station the switching means normally maintains at least one of the data terminals connected to the communication line in on-hook condition prior to initiation of a call, the method of operation, for an incoming call, comprising:

  • A. permitting the one data terminal, responsive to a ring signal received on the communication line, to go off-hook;

    B. disconnecting the one data terminal from the communication line, by operation of the switching means, without signalling an on-hook condition to the communication line;

    C. monitoring the communication line for occurrence of a recognition signal within a given recognition time interval T3; and

    D. actuating the switching means to connect only the first data terminal to the communication line, off-hook, to complete the call to the first data terminal, when a recognition signal from the first transmission standard is identified during interval T3 in step C; and

    E. actuating the switching means to connect only the second data terminal to the communication line, off-hook, to complete the call to the second data terminal when no recognition signal from the first transmission standard is identified during interval T3 in step C.

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